This invention relates generally to medical ultrasonic diagnostic systems, and more particularly the invention relates to a portable ultrasonic diagnostic instrument which operates at low power.
Modern ultrasonic diagnostic systems are large, complex instruments. Today""s premium ultrasound systems, while mounted in carts for portability, continue to weigh several hundred pounds. In the past, ultrasound systems such as the ADR 4000 ultrasound system produced by Advanced Technology Laboratories, Inc., were smaller desktop units about the size of a personal computer. However, such instruments lacked many of the advanced features of today""s premium ultrasound systems such as color Doppler imaging and three dimensional display capabilities. As ultrasound systems have become more sophisticated they have also become bulkier.
Disclosed in U.S. Pat. No. 5,722,412 is a diagnostic ultrasound instrument which exhibits many of the features of a premium ultrasound system in a hand-held unit. The instrument can be produced as a single unit or, in a preferred embodiment, the instrument is a two part unit one including a transducer beamformer an image processor and the other including a display and power source for both units. In such a configuration the transducer/processor unit can be manipulated with one hand while a cable between the two units enables the video to be shown on the display unit while the latter unit is held or positioned for optimal viewing of the ultrasound image. The cable also provides energy for the transducer/processor unit from the display.
In a preferred embodiment the ultrasound system from the transducer to the video output is fabricated on four types of application specific integrated circuits (ASICs): a transmit/receive ASIC which is connected to the elements of an array transducer, a front end ASIC which performs and controls transmit and receive beamforming, a digital signal processing ASIC which provides processing of the ultrasound signals such as filtering, and a back end ASIC which receives processed ultrasound signals and produces ultrasound image data. The image can be displayed on either a standard monitor or on a liquid crystal display (LCD). The elements of the unit including the ASIC can be fabricated on a single printed circuit board, thus eliminating the problems conventionally posed by connectors and cables. This sophisticated ultrasound instrument can be manufactured as a hand held unit weighing less than five pounds.
A limiting factor in portable ultrasonic diagnostic instruments is the power required for operation. Typically at least 35 watts of power are required for digital beamforming instrument whereas an analog beamforming instrument requires a minimum of 15 watts of power. The digital beamformer is more precise in performance, but the analog to digital and digital to analog signal conversions require considerably more power than the analog beamformer which requires no conversion and relies on phase modulation in beamforming.
The present invention is directed to providing a portable ultrasonic diagnostic instrument, either digital, analog or hybrid, with reduced power in operation.
In accordance with the invention a portable ultrasonic diagnostic instrument is provided which includes an array transducer, a beamformer for delaying and combining echo signals received by elements of the array transducer, signal processing and imaging circuitry for processing the echo signals, and a display for the processed echo signals, wherein the instrument operates on no more than 25 watts of electrical power. In one embodiment with an analog beamformer, the instrument operates on no more than 10 watts of power.
More particularly, the portable ultrasonic diagnostic instrument operates from battery power, and power control is provided for limiting power consumption in the instrument to 25 watts for a digital beamformer instrument or 10 watts for an analog beamformer instrument. Before operation of the instrument, various modes of operation are evaluated for required circuit functions, and other circuit functions are powered down or turned-off to conserve power. For example, B mode scanning does not require color power angiography and this function is turned-off. Similarly, sampling at a lower rate allows the analog to digital function to operate at a lower frequency thus reducing power consumption. In a sleep mode, the monitor display intensity can be diminished. Further, during operation of the instrument current from the battery source to the instrument components is monitored, and when the current reaches a first selected power limit, first functions in the instrument are altered to thereby reduce power consumption. For example, function can be the display of processed signals, and the display can be shifted in mode from active scanning to a mode selected from freeze and sleep which require less power. Additionally, un-needed functional blocks such as color display and 3D display of processed signals can be turned off. In a digital beamformer instrument, considerable power is expended in the analog to digital conversion of signals from the ultrasound transducers, and power can be conserved by reducing the clock frequency to the analog to digital converters. Similarly, the clock frequency to the digital signal processor of the instrument can reduced with attendant power savings. Thus, power reduction can be effected before instrument operation and/or during operation.
In an alternative embodiment, current from the battery source is monitored during instrument operation and first functions in the instrument operation are altered when the power consumption has reached a first power limit, and additional functions when monitored current reaches a second power limit whereby instrument operation is altered in steps. An ultimate threshold can be reached wherein the instrument operation is terminated entirely until troubleshooting of the instrument for possible failure is completed.
The invention and objects and features thereof will be more readily apparent from the following detailed description and appended claims when taken with the drawings.